The invention relates to methods and apparatus for testing fluid operated tools. The apparatus is directed to the testing of pneumatic jack legs and air operated drills used in underground mining of ore.
Air drills are used in underground mining to drill horizontal, slant or vertical holes in the rock or ore. Air drills were developed in 1930-35 for underground coal, silver, diamond, gold and metal mining. These air drills are made by only four (4) companies, which are: TOYO (Japan), Secan (Canada made in South Africa), IR, and Midwest (United States).
In use, the air drills are mounted on a jack leg which is an expandable piston and cylinder assembly. The air drill is mounted on one end of the jack leg. The other end of the jack leg has a crows foot adapted to be anchored on a support such as a floor or wall of the mine shaft. The operator of the air drill uses the jack leg to force a tubular drill into the rock or ore. The operator also regulates the speed of rotation of the drill.
The air drill and jack leg have a number of seals and tubes which over time can fail. When the seals leak air, the air drill and jack leg cannot be used and must be repaired. The conventional practice is to take the air drill and jack leg apart and replace the parts or rebuild this equipment. A mechanic in the mine shop can rebuild about seven jack legs in a 12 hour mining shift. The following U.S. Patents are related to methods and apparatus for testing air drills.
R. A. Chambers in U.S. Pat. No. 842,136 discloses a method and apparatus for testing pneumatic tools, such as rock drills. The pneumatic drill is connected to a piston of a testing cylinder. The piston is moved against a body of water to compress a column of air. The amount of air compressed is measured against the air consumed in operating the test machine. The air pressures, volume, and temperature data is used to calculate the efficiency of the drill.
L. Pryce in U.S. Pat. No. 1,576,465 discloses a method and apparatus for testing a hammer rock drill having a piston and tool chuck. A standard drill is used and operated to provide an index of the working capacity of the drill. The test drill is operated under the same conditions as the standard drill. A comparison of the rotational speeds of the tool chuck provides data as to efficiency of the test drill.
H. H. HAMAN in U.S. Pat. No. 2,909,922 discloses a portable testing device for rock drills for checking on repair work and determining when repairs are required. A brake is rotated by the test drill. The force applied to the brake is registered on a gauge which indicates the braking force. The pressure reading of the gauge is compared with a standard operating drill to determine the performance of the test drill.
Edwin J. Deremo et al in U.S. Pat. No. 4,901,587 describes a drill fixture for comparing the performance of a test drill with a simulated load. The linear drill travel and drill RPM are compared with standard data to determine operational effectiveness of the drill.
Gerard T. Pittard et al in U.S. Pat. No. 5,277,055 discloses a test stand for providing information as to impact energy and rotary speed of a drilling tool. This information is compared with a database in a computer as to the past history of the tool and the manufacturer""s recommended operating specifications to provide information regarding the operational efficiency of the test drill.
The apparatus of the invention is used to test the air drill and jack leg to determine the location of the defective seal or part. The defective seal or part is replaced without taking the entire air drill or jack leg apart. The mine mechanic can repair about 60 jack legs in a 12 hour mining shift. The test apparatus of the invention saves considerable time, labor and cost. The number of parts for repair of this equipment is reduced as only the broken or defective parts are fixed.
The test apparatus has an upright beam movably supporting a weight which provides a reaction force for an expandable jack leg. The jack leg has an upright cylinder accommodating one or more pistons and seals. A test stand having air pressure gauges and valves is connected with air lines to the jack leg. Air pressure is selectively applied to the jack leg located under the weight to test the effectiveness of the seals in the jack leg. Defect seals are replaced to place the jack leg in operative condition. The test stand also has air pressure gauges and a water pressure gauge and valves connected with air lines to the air drill to locate air and water leakage in the air drill and controls for the air drill. The test apparatus provides information then isolates the defective parts of the air drill and its controls. This allows the repair of the air drill with only replacement of the defective parts. There is a substantial saving of labor time and cost of repairing jack legs and air drills by identifying the defective parts of the jack legs and air drills and only replacing these parts.